An electrowetting display device is known in which a picture element includes a first fluid in the form of a colored oil acting as an optical switch. An electric field in the picture element is used to displace the oil. Without electric field the oil forms an opaque layer which blocks light; with electric field the oil contracts and allows light to transmit through the picture element.
The electric field in the known picture element is applied by an electrode that covers only part of the area of the picture element. The lower electric field in the area of the picture element without electrode causes the oil to contract to this area. The shape of the electrode provides control of the motion of the oil.
It is desirable to improve the control of the motion of the first fluid on application of an electric field.